This invention relates to an article useful in connection with the suction-assisted drainage of fluids, including gases, such as air, and liquids, such as blood, from a body cavity. More particularly, it relates to an article comprising inlet means to pass fluids therethrough to a liquid collection container from said body cavity, one-way valve means attached to the end of said inlet means to pass such fluids to said container when open and prevent the flow of gases therethrough, to the body cavity, when the valve is closed due to the pressure within the cavity being less than at the discharge end of said valve.
Violations of body cavities may occur for any of a number of reasons such as surgery, wounds or, in the case of pleural space invasion, rupture caused by coughing or disease. As a consequence atmospheric air, body gases and other fluids may invade the cavities and, e.g., in the case of pleurae, fill the pleural spaces thereby decreasing the lung capacity. If sufficient fluids accumulate the intimate contact between pleura and lung would be broken thereby preventing the outward pull of the pleura on the lung which results in shrinkage of the lung, i.e., a "collapsed" lung.
Another possible deleterious consequence of such a pleural space invasion would be a mediastinal shift in which the mediastinum, or space between the lungs, which contains such organs as the heart, is displaced from the center thereby compressing said organs. This could result in blood circulation problems and heart cessation.
Thus, it is desirable to remove such invasive fluids from the body cavities as quickly and completely as possible.
A typical prior art system for the collection of drained fluids from a body cavity includes three chambers connected in series. (Throughout this application a body cavity will be illustrated by pleural space and both terms will be used interchangeably.) They are first, a drainage collection chamber; second, a water seal chamber and third, a suction control chamber. The collection chamber accumulates any liquids drained from the body cavity. An air line passes from said chamber to the water seal chamber wherein the downstream end of said air line is positioned below the water level. The water seal chamber serves to maintain the vacuum pressure in the body cavity by preventing gases from passing upstream through the collection chamber to the body cavity, in the event the pressure therein decreases relative to the downstream pressure, thereby contaminating the body cavity. The water seal chamber is kept under vacuum. Because suction is maintained on the collection chamber air can reflux therethrough to the body cavity unless water (or another liquid) intervenes to prevent it. The depth of the end of the air tube below the water level in the water seal chamber controls the vacuum pressure at which the body cavity is drained. During the expiration of the patient, air drawn from the pleural cavity will pass to the water seal chamber where bubbling in the water seal will occur. The third, or suction control, chamber also provides water intervention above which the vacuum is maintained by direct connection to a vacuum source, generally a vacuum pump. The water intervention therein is directly connected to the atmosphere. While suction is being applied air will be drawn from either the connection to the atmosphere or the water seal chamber, i.e., from the source of least resistance. As long as the air moves from the atmospheric connection, the negative pressure in the pleural cavity will remainm constant. The pressure therein is controlled by the level of liquid in the suction control chamber.
The system described above, is typical of what will be referred to hereinafter as a "wet" drainage system. I.e., a system dependent upon liquid seals and the heights thereof for maintenance of vacuum in the pleural cavity and to prevent backflow of gases to the body cavity.
Such an apparatus is marketed by the Deknatel division of Howmedica, Inc. under the trademark PLEUR-EVAC.
A similar system which adds an additional suction control chamber, to allow the user to set both minimum and maximum vacuum levels within the body cavity is the THORA-TROL.TM. sold by Snyder Laboratories, Inc. of Dover, Ohio. This added feature permits the maintenance of vacuum despite incidents of negative pressure caused by coughing, for example, whereby the lung tissue is protected from sudden suction induced trauma.
Many other "wet" drainage systems have been described all of which are of interest but are not relevant in connection with the instant invention.
For instance, U.S. Pat. No. 4,540,413, to Russo, describes a system which will permit the drained fluids to be removed from the drainage chamber without disconnecting the unit from the patient. However, this unit depends upon a liquid seal in the rainage chamber to prevent entry of atmospheric air to the body cavity. Such a system suffers from the major drawbacks of the above devices, that is that an instantaneous decrease of pressure within the body cavity, e.g., due to gasping respiration of the patient could result in aspiration of the fluids within said chamber, including additives thereto such as anti-clotting agents, back into the body cavity or the increasing level of liquid in the chamber might progressively resist the drainage.
Furthermore, such a decrease in body cavity vacuum could result in reflux of the exuded gases thereinto before there is any, or much of a, liquid seal if such a seal depends upon the liquid draining from the cavity.
In addition, any debris present in the draining liquid might build up in or about the drainage tube thereby partially or completely clogging it. This could result in slower, or complete cessation of, drainage with the concomitant deleterious effects of poor drainage and/or excess pressure buildup in the body cavity.
All of the above systems suffer from the disadvantage of being cumbersome and position dependent in that any changes in the height of the liquid seals in the suction and/or water seal chambers thereof will affect the pressure applied to the body cavity.
Thus, in the prior art systems utilizing liquid seals to prevent backflow into the body cavity positioning of the unit in other than the customary vertical position, e.g., by upsetting thereof, could cause loss of such seals with increased vulnerability of the patient to pneumothorax. Such could not occur in the case of the instant invention which will close when the body cavity pressure is negative, relative to the vacuum chamber, regardless of the positioning of the unit.
In addition changes in water level as a result of, e.g., evaporation or entrainment in the evacuated gases might also affect accurate control of pressures within the system. To overcome those problems constant monitoring of, or periodic additions of water to maintain, the liquid levels of the water seal containing chambers is required with their concomitant cost in personnel time and potential for operator errors.
To avoid the above problems Heimlich, in U.S. Pat. No. 3,463,159 describes a one-way valve means to be attached to the discharge end of the inlet means which will prevent flow of gases therethrough to the body cavity when the pressure therein becomes less than that at the discharge end of the valve.
However, said device does not suggest nor teach the use of negative pressure indicating means to monitor the staus of the vacuum within the body cavity nor means for equilibrating said cavity with the environment at the discharge end of the one-way valve means.
Furthermore, in order to monitor functioning of the drainage system Heimlich also interposes a water seal between the body cavity and the vacuum source. Such an interposition will, of course, suffer from the limitations discussed above.
Throughout this specification the term `dry` as used in connection with the present invention refers to the fact that no liquid seals are required for any reason, e.g., to prevent backflow of gases or control negative pressure in the body cavity. It does not imply that no liquids are present in the drainage chamber.
The present invention overcomes the above disadvantages by providing a cap assembly, for a liquid collection container, said cap assembly being removable from the container to render the patient ambulatory, comprising one-way valve means, to operate without intervention of liquid seals and independent of position, to prevent backflow of gases into the body cavity when the pressure therein becomes less than that of the environment, and negative pressure indicating means to permit monitoring of the condition of the patient even when the inlet means are closed by the one-way valve means, e.g., when the patient is ambulatory. If desired, the cap assembly will further comprise negative pressure relief means to permit entrance of gases to the body cavity to equilibrate same with the environment at the discharge end of the one-way valve means.